Huh??? 11hz from this lil flea box? British miracle or Bollocks?

[killdozzer]

I think more people would use them if they could hear the difference with vs without in a quick demo. Well, the WAF and interior detonator objections are a huge part of it, though.

Which panels did you buy?

Oh, tell me about WAF!!! My lady asked me what am I typing around forums all day, so I explained and showed the sub. WHAT a mistake. Now she just keeps asking if the price dropped.

 

[highfigh]

Oh, tell me about WAF!!! My lady asked me what am I typing around forums all day, so I explained and showed the sub. WHAT a mistake. Now she just keeps asking if the price dropped.

If you're in the mood for an argument, ask why she has so many shoes.

 

[killdozzer]

If you're in the mood for an argument, ask why she has so many shoes.

HA!!! I accept your joke fully, but she's a bit different. I honestly believe she has fewer pairs than me!

 

[pcosmic]

Yes, I wondered about the big brother, the KEF KF92. Even with that one I was on the ledge. Looked for white papers, for independent measurements... Didn't find any. I expected the lot at ASR to be more critical about it and I was surprised they weren't. I posted the results of a xmax calculator and they blocked me from further posting. I'm at awe to see such brand devotion at ASR. Maybe KEF is a donor.

Long story short;
View attachment 44192

The membrane should travel almost 4cm in one direction to achieve 20Hz (THAT'S 20 not the stated 11!!) And almost 8cm looking both ways. And that's for less than useful 80dB.

They mention a different suspension and a proprietary DSP that progressively changes how deep it will go as you turn on the volume.

If I see exact measurements for this, I'm perfectly willing to take it all back. Until then, I CAN'T and DON'T believe they found a way to outsmart laws of physics.

Sorry to hear that the ASR lemmings curbed your freedom of technical inquisition....Rythmik notes that their small FM8 model with the dual 8 inch drivers can hit ~96ish db @ 20 Hz. Aside from them, I think all the other small subs with outlandish claims like this KEF are just hot air filled bollocks. I am curious about the Tekton 2-10 with the dual 10 inch drivers however. Would be nice to see measurements on those.

 

[Trell]

I think more people would use them if they could hear the difference with vs without in a quick demo. Well, the WAF and interior detonator objections are a huge part of it, though.

Which panels did you buy?

The Impression and Alpha Series from GIK looks very nice, especially the Impression and that helps with the WAF.

Sadly, just a few panels is not enough: Much area should be covered with as thick as possible panels, and that can be a practical problem. For my small living room 100 mm (4 inch) thick panels is just about max thickness (they absorb to about 100 Hz) though I would have liked thicker it's just not an option for now.

Back wall panels: https://gikacoustics.eu/product/impression-series-100mm-bass-trap-diffusor-absorber/
Front wall and roof panels: https://gikacoustics.eu/product/4a-alpha-panel-diffusor-acoustic-panel-bass-trap/
Back wall wall/ceiling corner: https://gikacoustics.eu/product/demi-impression-series-corner-bass-trap/
Front wall wall/ceiling corner: https://gikacoustics.eu/product/corner-ct-alpha-bass-trap/ and https://gikacoustics.eu/product/demi-ct-alpha-series-corner-bass-trap/

 

[killdozzer]

What boggles me is I think I could write their marketing better and come out a winner hands down both for specs and honest marketing and would carry on the tradition of KEF being reliable, respected, number-based, fairly priced company:

KEF KC62 will bring the performance of your Wireless LSX system as close to a full range system as possible given its size. Your desktop audio and PC gaming will be at the very top of the game. With full devotion from KEF, aesthetics are almost as pleasing as the audio performance. Both easy to place and on the eye!

KEF KC62 - "For a small listening room with studio sound"

KEF KF92 - If there's one decent use of the word bespoke, it's this; KF92 is the LS50's bespoke low end. Match made in heaven or in KEF, you tell us: visual match, easy to integrate, they pick up where the LS50 left off, size matched for the room it was intended for and design matched... It is superbly controlled, neutral and transparent and much like the LS50, the most you'll get for the size.

KEF KF92 - "Thinking of extending the performance of LS50? So were we.

 

[shadyJ]

Sorry to hear that the ASR lemmings curbed your freedom of technical inquisition....Rythmik notes that their small FM8 model with the dual 8 inch drivers can hit ~96ish db @ 20 Hz. Aside from them, I think all the other small subs with outlandish claims like this KEF are just hot air filled bollocks. I am curious about the Tekton 2-10 with the dual 10 inch drivers however. Would be nice to see measurements on those.

Rythmik's claim also deserves skepticism. In the case of any of these manufacturers' claims, there are a lot of different ways to inflate performance numbers. 20Hz? Sure, any sub can do 20Hz, but at what SPL and what distance and with how much THD+N? If sub manufacturers do not give you context for their claims, they should be dismissed. And even if they DO give you context for their claims, they should be verified by a third-party.

As for KEF's driver idea, it is kind of like one I had some time ago. I had an idea for opposite-facing drivers that used the same motor, but my idea was to use a field-coil motor where KEF has stuck with a fixed magnet motor. I think they could actually have done without the magnet by switching one of the coils 180 degrees out of phase and used each coil's magnetic field against each other to induce force. In the old days, before magnetized ferrite could be shaped to use in industrial applications, loudspeakers used to use another charged coil as the fixed magnet. The coils would have a constant charge and behave like a regular magnet.

 

[killdozzer]

Rythmik's claim also deserves skepticism. In the case of any of these manufacturers' claims, there are a lot of different ways to inflate performance numbers. 20Hz? Sure, any sub can do 20Hz, but at what SPL and what distance and with how much THD+N? If sub manufacturers do not give you context for their claims, they should be dismissed. And even if they DO give you context for their claims, they should be verified by a third-party.

As for KEF's driver idea, it is kind of like one I had some time ago. I had an idea for opposite-facing drivers that used the same motor, but my idea was to use a field-coil motor where KEF has stuck with a fixed magnet motor. I think they could actually have done without the magnet by switching one of the coils 180 degrees out of phase and used each coil's magnetic field against each other to induce force. In the old days, before magnetized ferrite could be shaped to use in industrial applications, loudspeakers used to use another charged coil as the fixed magnet. The coils would have a constant charge and behave like a regular magnet.

There's some talk about coils not matching in both drivers. You think that's possible?

 

[Irvrobinson]

Yes, I wondered about the big brother, the KEF KF92. Even with that one I was on the ledge. Looked for white papers, for independent measurements... Didn't find any. I expected the lot at ASR to be more critical about it and I was surprised they weren't. I posted the results of a xmax calculator and they blocked me from further posting. I'm at awe to see such brand devotion at ASR. Maybe KEF is a donor.

Long story short;
View attachment 44192

The membrane should travel almost 4cm in one direction to achieve 20Hz (THAT'S 20 not the stated 11!!) And almost 8cm looking both ways. And that's for less than useful 80dB.

They mention a different suspension and a proprietary DSP that progressively changes how deep it will go as you turn on the volume.

If I see exact measurements for this, I'm perfectly willing to take it all back. Until then, I CAN'T and DON'T believe they found a way to outsmart laws of physics.

Oh come now; this is a misleading explanation of what happened. You did not get "blocked from further posting" in a general sense, you got a reply ban for a specific KEF Unicore thread. Also, you apparently did not get blocked because of posting an xmax calculator. You got blocked for obsessive postings about the KEF being "a BS product", in that thread and separately in a dedicated thread you started. ASR is more tightly moderated than AH, and the moderator (there is only one) doesn't tolerate ranting like this.

 

[shadyJ]

There's some talk about coils not matching in both drivers. You think that's possible?

I don't know the details, but KEF has the resources to make this kind of driver work, so I wouldn't worry about it. For my own idea, you would need the coils and formers to have matching mass, and that means they have to have a different number of windings since one is slightly larger diameter coil which means somewhat different electrical characteristics, but that is a problem that would be easy to solve. As was said before, this technology is better for loudspeakers than subwoofers. I bet this design was inspired by the KEF Blade's bass drivers. They share the same frame but not the same motor.

 

[shadyJ]

Oh come now; this is a misleading explanation of what happened. You did not get "blocked from further posting" in a general sense, you got a reply ban for a specific KEF Unicore thread. Also, you apparently did not get blocked because of posting an xmax calculator. You got blocked for obsessive postings about the KEF being "a BS product", in that thread and separately in a dedicated thread you started. ASR is more tightly moderated than AH, and the moderator (there is only one) doesn't tolerate ranting like this.

That is what gives Audioholics' forums its extra zest, we say go ahead and rant till your heart is content, but you may be faced with ridicule from other posters. I don't care until you guys start flinging death threats at each other, and even then I will might them a pass if the death threats are interesting and creative.

 

[highfigh]

There's some talk about coils not matching in both drivers. You think that's possible?

Sure it's possible and I can think of a few reasons why they might do it (aside from the ones they mention- tuning to one frequency with absolute precision is difficult and it may also be done to augment or cancel something that one driver produces which isn't as good as they wanted. It would help in tuning the driver response in the cabinet, rather than changing the cabinet. Also, using the drivers in this configuration makes it an isobaric design, which is a good way to put two drivers in a very small enclosure.

Seeing that it has different equalization settings, I'm not sure it hits 11Hz with the same impact as a larger driver, but with an accelerometer, EQ, level matching and DSP control, it could produce lower than usual frequencies. It is sealed, so it's not a matter of dealing with the problems that come from operating below the port tuning frequency.

 

[killdozzer]

Sure it's possible and I can think of a few reasons why they might do it (aside from the ones they mention- tuning to one frequency with absolute precision is difficult and it may also be done to augment or cancel something that one driver produces which isn't as good as they wanted. It would help in tuning the driver response in the cabinet, rather than changing the cabinet. Also, using the drivers in this configuration makes it an isobaric design, which is a good way to put two drivers in a very small enclosure.

Seeing that it has different equalization settings, I'm not sure it hits 11Hz with the same impact as a larger driver, but with an accelerometer, EQ, level matching and DSP control, it could produce lower than usual frequencies. It is sealed, so it's not a matter of dealing with the problems that come from operating below the port tuning frequency.

THX, that's interesting, but I remember reading someone saying there's a reason why this particualr design doesn't qualify for isobaric... I forgot why. I'd have to look it up again.

 

[highfigh]

THX, that's interesting, but I remember reading someone saying there's a reason why this particualr design doesn't qualify for isobaric... I forgot why. I'd have to look it up again.

I think it would have to do with the fact that the drivers aren't 'identical' (choosing two of the same model being considered 'close enough').

 

[pcosmic]

Rythmik's claim also deserves skepticism. In the case of any of these manufacturers' claims, there are a lot of different ways to inflate performance numbers. 20Hz? Sure, any sub can do 20Hz, but at what SPL and what distance and with how much THD+N? If sub manufacturers do not give you context for their claims, they should be dismissed. And even if they DO give you context for their claims, they should be verified by a third-party.

Am i right in thinking all of Rythmik's claims have been in full compliance with CEA2010 thus far? Has anyone tested the FM8?

 

[killdozzer]

I think it would have to do with the fact that the drivers aren't 'identical' (choosing two of the same model being considered 'close enough').

Yep, that was it. You answered before I could find it.

 

[highfigh]

Yep, that was it. You answered before I could find it.

It's my cat-like reflexes that makes me different. Yeah, that's what makes me different......

 

[Ponzio]

Far from it!! Until now the performance from sucha small box is simply unmatched even if it's 20Hz at 80dB. So why not just say that? As I said it would still get the gold medal.

Is this what you're talking about?

 

[Ponzio]

KEF's description.

 

[shadyJ]

Am i right in thinking all of Rythmik's claims have been in full compliance with CEA2010 thus far? Has anyone tested the FM8?

Rythmik has never made any claims that had anything to do with CEA-2010. They don't provide any data except for a basic frequency response graph. As far as I know, no one has tested an FM8. I wouldn't expect it to knock anyone's socks off if it did get tested. Keep in mind the total surface area of two 8" woofers does not even equal that of a 12" woofer. The advantage is that two woofers will have two voice coils and potentially better power handling and thermal behavior than a single coil The disadvantage is that there is no a lot of room for suspension, so it is relatively tight for a serious subwoofer driver meaning lower efficiency at deep bass frequencies. That is probably why Rythmik harps on the mid-bass abilities of the FM8 so much, because its deep bass capability will be extremely limited.